var Base64 = {
  // private property
  _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

  // public method for encoding

  encode: function (input) {

    var output = "";

    var chr1, chr2, chr3, enc1, enc2, enc3, enc4;

    var i = 0;

    input = Base64._utf8_encode(input);

    while (i < input.length) {
      chr1 = input.charCodeAt(i++);

      chr2 = input.charCodeAt(i++);

      chr3 = input.charCodeAt(i++);
      enc1 = chr1 >> 2;

      enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);

      enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);

      enc4 = chr3 & 63;
      if (isNaN(chr2)) {

        enc3 = enc4 = 64;

      } else if (isNaN(chr3)) {

        enc4 = 64;

      }
      output = output + this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) + this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);
    }
    return output;

  },
  // public method for decoding

  decode: function (input) {
    var output = "";

    var chr1, chr2, chr3;

    var enc1, enc2, enc3, enc4;

    var i = 0;
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
    while (i < input.length) {
      enc1 = this._keyStr.indexOf(input.charAt(i++));

      enc2 = this._keyStr.indexOf(input.charAt(i++));

      enc3 = this._keyStr.indexOf(input.charAt(i++));

      enc4 = this._keyStr.indexOf(input.charAt(i++));
      chr1 = (enc1 << 2) | (enc2 >> 4);

      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);

      chr3 = ((enc3 & 3) << 6) | enc4;
      output = output + String.fromCharCode(chr1);
      if (enc3 != 64) {
        output = output + String.fromCharCode(chr2);
      }

      if (enc4 != 64) {

        output = output + String.fromCharCode(chr3);

      }
    }
    output = Base64._utf8_decode(output);
    return output;
  },

  // private method for UTF-8 encoding

  _utf8_encode: function (string) {
    // string = string.replace(/\r\n/g, "\n");
    var utftext = "";
    for (var n = 0; n < string.length; n++) {
      var c = string.charCodeAt(n);
      if (c < 128) {

        utftext += String.fromCharCode(c);

      } else if ((c > 127) && (c < 2048)) {

        utftext += String.fromCharCode((c >> 6) | 192);

        utftext += String.fromCharCode((c & 63) | 128);

      } else {

        utftext += String.fromCharCode((c >> 12) | 224);

        utftext += String.fromCharCode(((c >> 6) & 63) | 128);

        utftext += String.fromCharCode((c & 63) | 128);

      }
    }
    return utftext;

  },

  // private method for UTF-8 decoding
  _utf8_decode: function (utftext) {

    var string = "";

    var i = 0;

    var c = 0;

    var c1 = 0;

    var c2 = 0;
    while (i < utftext.length) {
      c = utftext.charCodeAt(i);
      if (c < 128) {

        string += String.fromCharCode(c);

        i++;

      } else if ((c > 191) && (c < 224)) {

        c = utftext.charCodeAt(i + 1);

        string += String.fromCharCode(((c & 31) << 6) | (c1 & 63));

        i += 2;

      } else {

        c1 = utftext.charCodeAt(i + 1);

        c2 = utftext.charCodeAt(i + 2);

        string += String.fromCharCode(((c & 15) << 12) | ((c1 & 63) << 6) | (c2 & 63));

        i += 3;

      }
    }
    return string;
  }
}
module.exports = Base64
